The purpose of this project is to define the regions of the brain, the neuronal pathways, and the neurotransmitter systems, which control endocrine, metabolic and autonomic responses to internal stimuli and to various types of stress and the effects of drugs on these systems. Studies on intracerebral injections of various peptides which are selective agonists of different types of opiate receptors have shown that mu-receptors modulate cardiovascular effects. Vasopressin mediation of baroreflexes in the brain and its role in sustaining blood pressure responses to baroreceptor deafferentation were examined.